Magnetic disc cartridge with counter display secured against inadvertent displacement

Abstract

A disc cartridge having a magnetic sheet jacket, a magnetic disc rotatably accommodated therein, and a window permitting the insertion of a magnetic head, is provided with a counter display member which is rotatably mounted in said jacket and surrounded, on the upper side of the jacket, by a graduated display scale and which has a keyhole-like aperture forming a radially oriented pointer and adapted to receive a drive pin. The counter display member is associated with an elastically acting click and pawl arrangement and has a first series of teeth formed on a flange-like portion of said counter display member and a click fixed to said jacket and elastically engaging the teeth of said first series of teeth and is also associated with a blocking device which keeps the counter display member in a firmly locked position as soon as it is mechanically disconnected from the drive pin.

What is claimed is: 
     
       1. A magnetic disc cartridge comprising a jacket; a magnetic flexible disc rotatably accommodated in said jacket; a window cut in said jacket and permitting the insertion of a magnetic head of an apparatus for recording and reproducing signals on the disc; a counter display member rotatably mounted in said jacket and being co-axially surrounded on the upper side of the jacket by a graduated display scale, said counter display member having a keyhole-like aperture forming a radially orientated pointer cooperating with said display scale; and elastically and permanently acting click and pawl arrangement including a first series of teeth formed on a section of a flange-like portion of said counter display member and a click fixed to said jacket and elastically engaging the teeth of said first series of teeth; a second series of teeth on an adjacent section of said flange-like portion; and a blocking device which engages said second series of teeth and thereby keeps the counter display member in a firmly locked position as soon as the cartridge is mechanically disconnected from said apparatus having the magnetic head. 
     
     
       2. A magnetic disc cartridge in which a magnetic disc and a cylindrical counter display member for displaying the number of recorded tracks on the magnetic disc are rotatably accommodated in a cartridge body, said cartridge comprising: a flange-like portion provided at an axially predetermined portion of said counter display member;   a first series of teeth and a second series of teeth formed respectively on one side of said flange-like portion and on the outer periphery thereof at a pitch corresponding to a unitary rotational angle of said counter display member; and,   within said cartridge body, a device for controlling rotation of said counter display member including a locking member engaging with at least a pair of the teeth of said second series of teeth formed on said outer periphery, a blocking member operative for securely holding said locking member in engagement with said second series of teeth of said outer periphery and a click member elastically engaging with at least a pair of the teeth of said first series of teeth formed on one side of said flange-like portion.   
     
     
       3. A magnetic disk cartridge according to claim 2; wherein said block member is movable in predetermined directions by operating means from the outside of the cartridge body and has a frontal wedge with an oblique edge, said locking member has a raised portion provided with an oblique edge which is adapted for engagement with said oblique edge of said frontal wedge so that said locking member is thereby moved in directions substantially perpendicular to said directions of movement of said blocking member for urging said locking member into engagement with at least a pair of said teeth of said second series of teeth. 
     
     
       4. A magnetic disc cartridge according to claim 2, wherein said click member includes a body and a click pawl connected to said body of the clock member by elastic arm portions, said clock pawl engaging elastically with teeth of said first series of teeth. 
     
     
       5. A magnetic disc cartridge according to claim 4; wherein said cartridge body includes upper and lower shells forming a jacket, and said lower shell has stoppers extending therefrom and by which said click pawl is prevented from being moved with said counter display member. 
     
     
       6. A magnetic disc cartridge according to claim 4; wherein said click pawl has a tip with angled faces including an angle bigger than an inter-tooth angle between two adjoining teeth of said first series of teeth. 
     
     
       7. A magnetic disc cartridge according to claim 3; wherein said cartridge body includes upper and lower jacket shells, undercut portions are defined by a protuberance provided on an inner wall surface of one lateral side of said lower jacket shell, and said blocking member is slidably retained in said undercut portions. 
     
     
       8. A magnetic disc cartridge according to claim 3; wherein said block member is spring biased by a coil spring in one of said directions by which said locking member is urged into engagement with a pair of teeth of said second series of teeth.